A variety of transducers, including rotary sensors, may produce sine and cosine signals based on the angle of rotation of a monitored device. The monitored device may be any device that moves in a rotary fashion over a 0 to 359 degree range, e.g., a steering wheel or a valve to name only a couple. From the sine and cosine input signals, the angle of rotation needs to be extracted.
A common method of extracting the angle of rotation, or θ, from sine θ and cosine θ signals is to encode each signal into a digital signal and then use a software routine, e.g., CORDIC routine, to extract θ. Essentially, the software routine solves the arctangent of the ratio of the sine θ and cosine θ values as detailed in equation (1).θ=ARCTAN(SIN θ/COS θ)  (1)
In order to extract θ using this method, it is necessary to convert an analog signal to a digital signal, e.g., via an A/D converter, to use some microprocessor or microcomputer to run the stored software routine, to store the software routine in memory, and to output the results via a D/A converter. Accordingly, there is a need for an alternative hardware apparatus for extracting a phase angle from sine and cosine signals.